As pointed out in this article by Om Malik at GigaOM there seems to be something wrong with Facebook.

In the euphoria around Facebook, many of us (and perhaps Mark Zuckerberg as well) forgot the real premise (and promise) of Facebook. In their overarching ambition to become a Microsoft like entity, Zuckerberg & Co. forgot that what makes them great is not the apps, but the ability to create a private, fun, controlled and easy to use environment. Then bankruptcy or bans won’t even be an issue.

You better remember some of those words if you’re planning on starting a social network >> private, fun and easy!